The present invention relates to an ink jet recording head for ejecting ink supplied from an ink tank in the form of ink drops, and a method of manufacturing the same.
A recording head of an ink jet recording head is composed of a head body for ejecting ink in the form of ink drops and an ink cartridge containing ink to be supplied to the head body. The recording head has an ink supply needle, and the ink cartridge has an ink supply hole. Ink is supplied to the head body through the ink supply needle that is inserted into the ink supply hole.
More precisely, in the recording head, as shown in FIG. 15, for example, a head body 1 for ejecting ink drops in accordance with a print signal is mounted on the lower side of a head holder 10. A cartridge case 12 for receiving an ink cartridge 2 is provided on the upper side of the head holder 10. A positioning protrusion 13 is formed on the lower side of the ink cartridge 2, and an ink supply hole 4 is formed under the positioning protrusion 13. The opening of the ink supply hole 4 is sealed with a film 14 till the ink cartridge 2 is set to the recording head.
A concavity 11 into which the positioning protrusion 13 is fit is formed in the upper side of the head holder 10, and an ink supply needle 3 stands erect in the concavity 11. In a recording head for color printing by use of a plurality of color inks, the ink cartridge 2 includes a plurality of ink chambers 15. As shown in FIG. 16, for example, the ink cartridge includes four ink chambers containing color inks of cyan, magenta, yellow and black. A plurality of ink supply holes 4 are provided in the ink cartridge 2. Specifically, the ink supply hole 4 is provided for each ink chamber 15 (viz., each color). Four ink supply needles 3 are also provided for those colors, respectively. FIG. 16 shows the recording head before the ink cartridge 2 is set to the head.
The tip of each ink supply needle 3 is shaped to be conical so that it can break through a film of the ink supply hole 4. Ink introducing holes 6 are vertically formed in a slanted surface 8 of the tip of the needle. A first ink passage 5, which communicates with the ink introducing holes 6, is formed in the ink supply needle 3. Second ink passages 7 for supplying ink to the head body 1 are formed in the head holder 10. A filter 9 for filtering ink supplied from the ink cartridge 2 is provided at the entrance of each second ink passage 7. In order to guide ink to the head body 1 that is shorter in width than the ink cartridge 2, the second ink passages 7 are obliquely extended toward the head body 1 centered (see FIG. 16).
When the ink cartridge 2 is set to the recording head, the tip of the ink supply needle 3 breaks through the film 14 which sealingly closes the ink supply hole 4 of the ink cartridge 2 and, the ink supply needle 3 is inserted into the ink supply hole 4. Then, in the recording head, ink is supplied from the ink cartridge 2 into the head body 1, through the ink introducing holes 6 of the ink supply needle 3 and the first and second ink passages 5 and 7.
The recording head, together with the ink cartridge 2, is carried on a carriage (not shown), and reciprocatively moved across a recording sheet by the carriage. Ink to be consumed is supplied from the ink cartridge 2 to the head body 1 via the ink supply needle 3 in a replenishing manner. During the widthwise movement of the recording head, the recording head ejects ink drops through its nozzle orifices toward the recording sheet, thereby effecting a print.
In the recording head mentioned above, to guide ink from the ink cartridge 2 to the head body 1 of which the width is shorter than that of the ink cartridge 2, the second ink passages 7 are obliquely extended to the head body 1. To manufacture the recording head, it is necessary to form the slanted holes requiring intricate work. Accordingly, the cost to manufacture will inevitably increase. Since the second ink passages 7 are slanted, there is a limit in reducing the height of the recording head per se. For this reason, the related recording head cannot meet the demand of size reduction in the recent ink jet recording heads.
Accordingly, an object of the present invention is to provide an ink jet recording head which is easy in working and assembling, low in cost, reduced in size, and is substantially free from entry of air bubbles into passages.
In order to achieve the above object, according to the first aspect of the invention, there is provided an ink jet recording head comprising:
a head body from which ink drops are ejected;
a channel forming plate provided with a groove;
a sealing plate for sealing each opened side of the grooves to form an ink supply channel for supplying ink from an ink tank to the head body.
In the thus constructed recording head, a portion forming the ink supply channel of the recording head is composed of two types of plate-like members. Therefore, the recording head may be remarkably reduced in size when comparing with the related one in which the ink supply channel is formed by use of slanted passage.
According to the second aspect of the invention, in the head according to the first aspect, the channel forming plate integrally includes a holder member for holding the ink tank, and the sealing plate is bonded to the holding member.
In the ink jet recording head, the working and assembling are easy, and cost to manufacture is reduced. In addition, the opened side of the respective grooves are sealed by bonding the sealing plate to the holding member.
According to the third aspect of the invention, in the head according to the first aspect, the channel forming plate is provided as an independent member.
In the ink jet recording head, the working and assembling are easy, and cost to manufacture is reduced.
According to the fourth aspect of the invention, in the head according to the third aspect, the channel forming plate defines at least a bottom portion and side walls of the respective grooves.
In the ink jet recording head, the grooves are formed by the channel forming plate and the sealing plate.
According to the fifth aspect of the invention, in the head according to the third aspect, the channel forming plate includes through holes which respectively define side walls of the grooves.
In the ink jet recording head, the grooves are formed by the channel forming plate, the sealing plate and a member for sealing one opening side of the through hole to define a bottom portion of the grooves.
According to the sixth aspect of the invention, in the head according to the first to fifth aspects, one longitudinal end portion of the respective grooves are communicated with the ink tank, and the other end portions are communicated with the head body.
In the ink jet recording head, the size of head body can be remarkably reduced irrespective of the size of ink tanks due to the arrangement of the grooves.
According to the seventh aspect of the invention, in the head according to the first to sixth aspects, the end portions of the respective grooves communicated with the head body are converged.
In the ink jet recording head, since the end portions of the grooves communicated with the head body are closely arranged, the size of head body can be remarkably reduced irrespective of the size of ink tanks.
According to the eighth aspect of the invention, in the head according to the seventh aspect, plural kinds of ink are ejected from the head body, and the grooves are provided so as to be associated with the ink kind.
In the ink jet recording head, plural kinds of ink can be supplied to the head body through the grooves and ejected therefrom.
According to the ninth aspect of the invention, in the head according to the first to eighth aspects, sealing compound is provided on the channel forming plate at least around the grooves.
In the ink jet recording head, the grooves of the channel forming plate is sealed with sealing compound. Accordingly, the ink supply channel is reliably formed, and there is less chance that dust and the like enter the channel.
According to the tenth aspect of the invention, in the head according to the ninth aspect, the channel forming plate and the sealing plate are fastened together with the sealing compound being located therebetween.
In the ink jet recording head, the groove of the channel forming plate is sealed with sealing compound. Accordingly, the ink supply channel is reliably formed, and there is less chance that dust and the like enter the channel.
According to the eleventh aspect of the invention, in the head according to any one of the first to tenth aspects, the sealing plate is welded to the channel forming plate.
In the ink jet recording head, the sealing plate is welded to the channel forming plate, so that there is less chance that dust and the like enter the ink supply channel. Further, the slanted passage requiring intricate work is not used, and the assembling is easy and manufacturing cost is low.
According to the twelfth aspect of the invention, in the head according to the eleventh aspect, a welding pin is provided on the channel forming plate and a through hole is formed in the sealing plate. The welding is performed by melting the welding pin inserted into the through hole.
In the ink jet recording head, the assembling of the recording head is easy and hence it is easy to make automating of the assembling process of the recording head. Welding residual substances are hard to be produced, while the ultrasonic welding is unlikely to yield them. Chance that dust and others enter the ink supply channel is further lessened.
According to the thirteenth aspect of the invention, in the head according to the twelfth aspect, the welding pin is provided a portion surrounding the grooves.
In the ink jet recording head, if an external force is applied to the sealing plate, the mounting structure of the plate and the channel forming plate is hard to be unsteady and ink leakage is unlikely to occur.
According to the fourteenth aspect of the invention, in the head according to the thirteenth aspect, a plurality of welding pins are provided so as to surround the grooves.
In the ink jet recording head, if an external force is applied to the sealing plate, the mounting structure of the plate and the channel forming plate is hard to be unsteady and ink leakage is unlikely to occur.
According to the fifteenth aspect of the invention, in the head according to any one of the first to fourteenth aspects, a filter for filtering ink supplied from the ink tank is comprised. The ink supply channel guides ink having passed through the filter to the head body.
In the ink jet recording head, no dust enter the ink supply channel which rejects the presence of dust and the like, and the recording head is extremely effective.
According to the sixteenth aspect of the invention, in the head according to any one of the ninth to fifteenth aspects, the sealing compound is made of silicone resin.
In the ink jet recording head, the sealing compound is hard to be deteriorated and aged by ink, and the ink leakage occurs less frequently.
According to the seventeenth aspect of the invention, in the head according to any one of the first to sixteenth aspects, the grooves are defined by a wall portion standing erect on the channel forming plate. A top surface of the wall portion is gradually slanted downward to the grooves.
In the ink jet recording head, the slanted surface being gradually slanted downward to the groove is provided. A gap on a portion of the slanted surface that is formed in a state that the surface of the channel forming plate is sealed with the sealing plate, is satisfactorily small. Accordingly, it can hold the sealing compound satisfactorily, and it is hard to flow over the gap. The recording head is substantially free from the problem of the flow of the sealing compound into the ink supply channel, which is unavoidable in the related recording head. Further, the ink ejection trouble arising from attachment of air bubbles to the sealing compound is also solved.
According to the eighteenth aspect of the invention, in the head according to the seventeenth aspect, a stepped portion on which sealing compound is to be applied is formed on an outer periphery of the wall portion.
In the ink jet recording head, the work to apply the sealing compound to the stepped portion is easy. The overflow of the sealing compound may be prevented by reducing the amount of sealing compound applied. In this case, if the amount of it is excessively reduced, control of the application of the sealing compound is impossible. In an extreme case, the supply of the sealing compound is interrupted, resulting in poor sealing. In this ink jet recording head, the sealing compound is applied to the stepped portion. Therefore, the amount of the sealing compound effectively contributing to the sealing is reduced when the sealing is effected by the sealing plate. For this reason, the overflow of the sealing compound can effectively be prevented without excessively reducing the amount of the sealing compound applied. The control of the amount of the sealing compound applied is also easy, and poor sealing is not caused.
According to the nineteenth aspect of the invention, in the head according to the seventeenth or eighteenth aspect, a slope of the slanted face is selected to be preferably within 5/1000 to 200/1000.
In the ink jet recording head, the gap on a portion of the slanted surface that is formed in a state that the surface of each of the channel forming plate is sealed with the sealing plate, is satisfactorily small. Accordingly, if air bubbles attach to the sealing compound, its amount is considerably small. Removal of the air bubbles from the sealing compound is difficult, thereby preventing poor ejection trouble.
According to the twentieth aspect of the invention, in the head according to the seventeenth or eighteenth aspect, in the head according to any one of the eleventh to thirteenth aspects, a flat portion is provided between the stepped portion and the slanted surface.
In the ink jet recording head, there is no chance of reducing the sealing effect between the channel forming plate and the sealing plate.
According to the twenty-first aspect of the invention, in the head according to the twentieth aspect, a corner demarcating the stepped portion and the flat portion is removed to form a tapered surface.
In the ink jet recording head, when the sealing compound applied to the stepped portion is held down by the sealing plate and spreads to the flat portion, the sealing compound stands on the tapered surface, and there is no excessive flow of the sealing compound to the flat portion. Therefore, prevention of the overflow of the sealing compound into the ink supply channel is further ensured.
According to the twenty-second aspect of the invention, in the head according to any one of the first to twenty-first aspects, the sealing plate is provided with ink supply holes for supplying ink from the respective ink supply channels to the head body. The ink supply holes are bored in the sealing plate obliquely such that an interval of openings of the respective holes on the side facing the channel forming plate is longer than an interval of openings of the respective holes on the side facing the head body. In the ink jet recording head, if the interval of the openings of the respective holes on the side facing the channel forming plate is set to be equal to that of ink supply passages of the head body, the interval of the openings of the respective holes on the side facing the head body becomes longer than that. Accordingly, a sufficient space is present, so that a sufficient width of the channel forming plate is secured in a portion of the channel forming plate corresponding to the ink supply hole. Such a problem of the related recording head that the sealing is poor and the sealing compound flows out into the passages is almost solved. The trouble caused by attaching air bubbles to the sealing compound, for example, poor ejection, is prevented.
According to the twenty-third aspect of the invention, in the head according to the twenty-second aspect, the grooves are defined by a wall portion standing erect on the channel forming plate. The width of the wall portion is 1.0 mm or longer over the entire circumference of the grooves.
In the ink jet recording head, such a problem of the related recording head that the sealing is poor and the sealing compound flows out into the ink supply channels is almost solved. The trouble caused by attaching air bubbles to the sealing compound, for example, poor ejection, is prevented with certainty.
According to the twenty-fourth aspect of the invention, in the head according to the twenty-second or twenty-third aspect, the respective openings of the ink supply holes facing the head body is circular in shape.
In the ink jet recording head, the openings of the ink supply holes of the resultant plate are simple in shape, the manufacturing cost is not high, the sealing performance is not degraded, and air bubbles being caught in the passages less happens. If the ink supply holes obliquely passing through the plate are formed by use of normal pins circular in cross section, the openings of the ink supply holes are elliptical. Therefore, it is necessary to shape the openings of the ink supply pipes of the head body to be elliptical, and hence to shape the packing applied thereto to be also elliptical.
Thus, the elliptical member needs to be used for the other member. The manufacturing cost of the overall device is increased. Further, the sealing is deteriorated, and air bubbles are easy to be caught. On the other hand, in the invention, the openings of the ink supply holes of the sealing plate are circular. Therefore, there is no need of making the elliptical openings of the ink supply pipes and the elliptical packing applied to those. Consequently, the manufacturing cost is low, good sealing is secured, and air bubbles are little caught in the passages.
According to the twenty-fifth aspect of the invention, in the head according to any one of the twenty-second to twenty-fourth aspects, a stepped portion is formed around the respective openings of the ink supply holes facing the channel forming plate.
In the ink jet recording head, there is substantially eliminated the deterioration of the sealing at the openings of the ink supply holes.
According to the twenty-sixth aspect of the invention, there is provided a method of manufacturing the ink jet recording head according to the sixteenth aspect of the invention, comprising the steps of:
disposing supply hole forming pins extending obliquely with respect to an inner face of a mold having a molding space in which the sealing plate is to be formed, the inner face corresponding to a surface of the sealing plate;
filling the molding space with molding material;
solidifying the molding material; and
pulling out the supply hole forming pins from the molded product to form the ink supply holes.
When the manufacturing method is used, the ink jet recording head of the invention may be manufactured at low cost and in an easy manner.
According to the twenty-seventh aspect of the invention, in the method according to the twenty-sixth aspect, both tip ends of the respective supply hole forming pins abutting against the inner face of the mold are circular in shape.
When the manufacturing method is used, the openings of the ink supply holes of the resultant plate are simple in shape, the manufacturing cost is not high, the sealing performance is not degraded, and air bubbles being caught in the ink supply channels less happens.
According to the twenty-eighth aspect of the invention, in the method according to the twenty-seventh aspect, one end portion of the respective supply hole forming pins which corresponds to the opening of the ink supply hole facing the channel forming plate is configured to have a large diameter.
When the manufacturing method is used, the stepped potion may be formed around the opening of each ink supply hole in a relatively simple manner. With provision of the stepped portion, the sealing performance is little degraded.